A zeolite separation membrane having a porous support and a zeolite layer (zeolite membrane) formed on its surface and inside its pores is widely used as a means of separation of a specific liquid component in a liquid mixture. Among zeolite separation membranes used for separation of a liquid mixture, faujasite (FAU) zeolite separation membranes, which have a layer of FAU zeolite crystals (Y- or X-type zeolite crystals), are of particular interest because of, for example, the facts that they can be used for separation of a mixture of different organic solvents, that they are excellent in durability, heat resistance, acid resistance and water resistance, and that they are safe to the human body.
As an example of a conventional process for production of an FAU zeolite separation membrane, there is known a process in which: an aluminosilicate gel having a prescribed composition is aged for a prescribed time, and then a porous support to which NaY zeolite crystals are attached is immersed in the gel and the hydrothermal synthesis is performed at a prescribed temperature for a prescribed time (see Patent document 1). There is also known a process in which: a porous support to which NaX zeolite crystals are attached is immersed in a reaction solution having a prescribed composition and is heated for reaction, and then it is immersed in distilled water (see Patent document 2).    Patent document 1: Japanese Patent Application Laid-Open No. 8-257301    Patent document 2: Japanese Patent Application Laid-Open No. 10-212117